This proposed research is concerned with the mechanism(s) involved in the suppression of reproductive performance or gonadal function during either spontaneous or induced hyperadrenal states. The general phenomenon of adrenal-gonad interaction is broad in scope since marked alteration of either gonadal or adrenal function appears to result in significant changes in pituitary-target organ relationships in the alternate system, e.g., adrenalectomy results in a marked decrease in LH secretion and/or LH release in the rat. Most studies concerned with hyperadrenalism effects have been conducted with naturally occurring hyperadrenal states or in experiments based on administration of exogenous ACTH or corticosteroids in intact animals. It is difficult to distinguish the effects of high circulating levels of ACTH from those of high endogenous secretion rates of ACTH. Furthermore, one cannot determine if the ACTH treatment produced a direct effect or was mediated by steroid products from the adrenal or by some other route. Thus, a determination of the precise effect of exogenous treatment with hormones such as ACTH, corticosteroids and other steroid products of the adrenal cortex can only be determined by use of adrenalectomized animals in which various hormonal concentrations and relationships can be artificially produced by infusion. Determination of the concentrations in plasma of certain major steroids other than corticoids produced by the adrenal shall be determined in ACTH-treated, gonadectomized animals. Animals will be studied during hormone administration (ACTH, corticoids, progesterone and other steroids) throughout the cycle. One aspect of this project will be concerned with CL development and function. These animals will be placed on treatment after ovulation has occurred. A second study will be concerned with occurrence of ovulation and these animals will be placed on experiment during proestrus. All protein hormones (ACTH, LH and prolactin) will be measured by RIA. Corticoids will be measured by competitive protein binding. Other steroids progesterone, estrogens and androgens will be measured by RIA techniques.